From Auditory Fatigue to Hearing Disorders? A Translational Study on Daily Noise Exposure. – FATIGAUDIT
The permissible exposure limit in many industrial countries is 85 dB(A) for an 8 hours working day. However, a daily noise exposure at 85 dB(A) is responsible for “auditory fatigue”, a temporary decrease of hearing sensitivity at the end of the day that has been largely ignored so far. When combining recreational and occupational noise exposures, approximately 13% of people are exposed to a cumulative daily dose of noise equal to, or exceeding, 85 dB(A). First, even transient hearing loss could have effects on cognitive performance through increased stress levels, learning difficulties, or the modulation of distraction and vigilance by the noise.
Second, it was recently shown that a noise-induced temporary decrease in hearing sensitivity could underlie neural and synaptic alterations in the peripheral auditory system, and that this can coexist with long-term normal auditory thresholds. From that perspective, auditory fatigue could be an early sign of damage to the peripheral auditory system.
The FATIGAUDIT proposal will investigate the risks of hidden damage to the auditory system and of impairment to auditory perceptual abilities at the workplace due to prolonged noise exposure. Investigations will be done in humans and gerbils, which have a peripheral auditory system very similar to humans from the perspective of its anatomy, its hearing range and, importantly, its sensitivity to daily noise exposure.
We will study damage to the cochlea at the cellular level and changes in the functional organization of the auditory cortex due to single or repeated daily noise exposure. We will also test whether the ability to identify and discriminate complex sounds in noise are impaired by auditory fatigue. These results will allow us to design methods to easily and quickly diagnose auditory fatigue at places where it occurs, including the workplace. In particular, innovative methods giving access to the activity of the auditory nerve, even in humans, will be tested and validated. Finally, preventing auditory fatigue by resting periods will be explored.
The FATIGAUDIT proposal brings together four complimentary fundamental, clinical and work-related research teams. The Institut de l’Audition (IdA, Institut Pasteur, coordinator) will provide expertise in noise-induced disorders and functional changes in animals’ central auditory system; The Institut des Neurosciences (INM, Montpellier) will bring its world-renowned expertise in the structure of the peripheral auditory system; The Centre Hospitalier Universitaire (CHU) in Montpellier will perform clinical tests and validation of auditory fatigue diagnosis in humans; the Institut National de Recherche et Sécurité (INRS, Nancy) will bring its unique expertise in measuring effects of occupational noise exposure directly at the workplace.
This ideally tailored consortium will be able to assess the cellular, functional, and cognitive aspects of auditory fatigue. Better understanding of this neglected risk for hearing and health will help to prevent the risk of long-term hearing disorders, and premature auditory ageing, in a significant part of the population, as well as reduce the social and financial burden of noise. This proposal also aims at questioning current occupational regulations as preliminary data from this consortium shows that these regulations do not prevent temporary hearing loss from occurring in many professions.
Monsieur Boris GOUREVITCH (IP - Plasticité des Circuits Auditifs Centraux)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
IP - Plasticité des Circuits Auditifs Centraux IP - Plasticité des Circuits Auditifs Centraux
CHU Montpellier frederic venail
INM Institut des Neurosciences de Montpellier
INRS Institut National de Recherche et de Sécurité pour la prévention des accidents du travail et des maladies professionnelles
Help of the ANR 696,557 euros
Beginning and duration of the scientific project: March 2022 - 48 Months